1. Technical Field
The present invention relates to a method and system for treating waste matter from animals, in particular farm animals; a urea-lean biogas fuel product; a urea-rich animal waste-matter product; and uses thereof, in particular in a method of controlling the content of nitrogen in manure, in a method of reducing gaseous ammonia in stables, in a stable for farm animals, in a biogas reactor system for producing biogas, in a method of producing urea from waste matter, in a method of producing urea formaldehyde, and in a method of producing biogas fuel from waste matter.
2. Background Art
Commercial utilisation of livestock in the production of meat from e.g. pig, cattle, or sheep produces large quantities of animal waste matter to be disposed.
Present methods of disposing animal waste matter include recycling thereof through the agricultural system e.g. by storage and spreading the animal waste matter such as animal manure on land, optionally spreading it on land after treatment thereof for removing excess polluting nutrients which cannot be absorbed in the soil. However, although such treatment methods provide improved disposable waste matter having reduced amounts of nutrients such as phosphorous, nitrogen-containing compounds, and accumulating minerals such as copper, the treated waste matter is still spread on the land. Consequently, lack of land sites with suitable capacity and risks of excess fertilisation or excess manuring resulting in undesired pollution put an upper limit to the amount of treated animal waste matter that can be disposed this way. Additionally, removed nutrients and minerals in the waste matter treatment would have to be disposed.
Consequently, there is a need for a method and apparatus for disposing animal waste matter which does not depend, or does not totally depend on disposal through the agricultural system.